Salt and cardiovascular disease
Common edible salt is the chemical compound known as sodium chloride.[7]
Effect of salt on blood pressure
The human body has evolved to balance salt intake with need through means such as the
The well known effect of sodium on blood pressure can be explained by comparing blood to a
Circulating water and
Salt restriction in chronic kidney disease
A 2021
DASH-Sodium study
The DASH-Sodium study was a sequel to the original DASH (Dietary Approaches to Stop Hypertension) study. Both studies were designed and conducted by the National Heart, Lung, and Blood Institute in the United States, each involving a large, randomized sample.[11] While the original study was designed to test the effects of several varying nutrients on blood pressure, DASH-Sodium varies only in salt content in the diet.[12]
Participants were pre-hypertensive or at stage 1 hypertension, and either ate a DASH-Diet or a diet reflecting an "average American Diet". During the intervention phase, participants ate their assigned diets containing three distinct levels of sodium in random order. Their blood pressure is monitored during the control period, and at all three intervention phases.[12]
The study concluded that the effect of a reduced dietary sodium intake alone on blood pressure is substantial, and that the largest decrease in blood pressure occurred in those eating the DASH eating plan at the lowest sodium level (1,500 milligrams per day).[12] However, this study is especially significant because participants in both the control and DASH diet group showed lowered blood pressure with decreased sodium alone.[11]
In agreement with studies regarding salt sensitivity, participants of African descent showed high reductions in blood pressure.[12]
Hypertension and cardiovascular disease
In 2018, the
As of 2019, major government research organizations, such as the US Centers for Disease Control and Prevention and the European Food Safety Authority, advise consumers to reduce their consumption of salt to lower the risk of cardiovascular diseases.[5][18] One 2016 review found that five studies were supportive of the evidence that reduced sodium intake lowers cardiovascular disease incidence and mortality, three contradicted this evidence, and two found insufficient evidence to reach a conclusion.[19] The survey found 27 primary studies and 106 letters in academic journals in support of the salt evidence, 34 primary studies and 51 letters contradicting the evidence, and 7 primary studies and 19 letters that were inconclusive.[19] There are several long-term studies which found that groups with sodium-reduced diets have lower incidences[spelling?] of cardiovascular disease in all demographics.[14]
Some researchers cast doubts on the link between lowering sodium intake and the health of a given population.[20]
Current trends and campaigns
Government regulatory agencies and clinical organizations, the
In 2015, the United States Centers for Disease Control and Prevention began an initiative encouraging Americans to reduce their consumption of salty foods.[21] The American Heart Association defined a daily sodium consumption limit of 1500 milligrams (contained in less than 0.75 teaspoon of table salt).[13][22]
According to a 2012 Health Canada report, Canadians in all age groups are consuming 3400 mg per day of sodium, more than twice as much as needed.[23] The US Centers for Disease Control and Prevention stated that the average daily sodium intake for Americans over 2 years of age is 3436 milligrams.[24] The majority of sodium consumed by North Americans is from processed and restaurant foods, while only a small portion is added during cooking or at the table.[21][25]
In the European Union, half of the member states legislated change in the form of taxation, mandatory nutrition labeling, and regulated nutrition and health claims to address overconsumption of sodium[26] in response to a 2012 EU Salt Reduction Framework.[27]
Sodium sensitivity
A diet high in sodium increases the risk of hypertension in people with sodium sensitivity, corresponding to an increase in health risks associated with hypertensions including cardiovascular disease.[28]
Unfortunately, there is no universal definition of sodium sensitivity; the method to assess sodium sensitivity varies from one study to another. In most studies, sodium sensitivity is defined as the change in mean blood pressure corresponding to a decrease or increase of sodium intake. The method to assess sodium sensitivity includes the measurement of circulating fluid volume and peripheral vascular resistance. Several studies have shown a relationship between sodium sensitivity and the increase of circulating fluid volume or peripheral vascular resistance.[29]
A number of factors have been found to be associated with sodium sensitivity. Demographic factors which affect sodium sensitivity include race, gender, and age.[30] One study shows that the American population of African descent are significantly more salt sensitive than Caucasians.[31] Women are found to be more sodium sensitive than men; one possible explanation is based on the fact that women have a tendency to consume more salt per unit weight, as women weigh less than men on average.[31] Several studies have shown that the increase in age is also associated with the occurrence of sodium sensitivity.[30]
The difference in genetic makeup and family history has a significant impact on salt sensitivity, and is being studied more with improvement on the efficiencies and techniques of genetic testing.[30] In both hypertensive and non-hypertensive individuals, those with haptoglobin 1-1 phenotype are more likely to have sodium sensitivity than people with haptoglobin 2-1 or 2-2 phenotypes. More specifically, haptoglobin 2-2 phenotypes contribute to the characteristic of sodium-resistance in humans.[32] Moreover, prevalence of a family history of hypertension is strongly linked with the occurrence of sodium sensitivity.[33]
The influence of physiological factors including renal function and insulin levels on sodium sensitivity are shown in various studies.[30] One study concludes that the effect of kidney failure on sodium sensitivity is substantial due to the contribution of decreasing the Glomerular filtration rate (GFR) in the kidney.[34] Moreover, insulin resistance is found to be related to sodium sensitivity; however, the actual mechanism is still unknown.[35]
Potassium and hypertension
Possible mechanisms by which high intakes of dietary potassium can decrease risk of hypertension and instances of cardiovascular disease have been proposed, but not extensively studied.[36] However, studies have found a strong inverse association between long-term adequate to high rates of potassium intake and the development of cardiovascular diseases.[36]
The recommended dietary intake of potassium is higher than that of sodium.[37] Unfortunately, the average absolute intake of potassium of studied populations is lower than that of sodium intake.[37] According to Statistics Canada in 2007, Canadians' potassium intake in all age groups was lower than recommended, while sodium intake greatly exceeded recommended intake in every age group.[38]
The ratio of potassium to sodium intake may account for the large difference in the occurrence of hypertension between primitive cultures eating diets made up of mostly unprocessed foods and Western diets which tend to include highly processed foods.[36]
Salt substitutes
The growing awareness of excessive sodium consumption in connection with hypertension and cardiovascular disease has increased the usage of salt substitutes at both a consumer and industrial level.[39]
On a consumer level, salt substitutes, which usually substitute a portion of sodium chloride content with potassium chloride, can be used to increase the potassium to sodium consumption ratio.[39] This change has been shown to blunt the effects of excess salt intake on hypertension and cardiovascular disease.[1][39] It has also been suggested that salt substitutes can be used to provide an essential portion of daily potassium intake, and may even be more economical than prescription potassium supplements.[40]
In the food industry, processes have been developed to create low-sodium versions of existing products.
There have been concerns with certain populations' use of potassium chloride as a substitute for salt as high potassium loads are dangerous for groups with
See also
- Salt
- Hypertension
- Cardiovascular Disease
References
- ^ PMID 27184271.
- ^ PMID 24322810.
- ^ "Salt". National Center for Chronic Disease Prevention and Health Promotion, Division for Heart Disease and Stroke Prevention. US Centers for Disease Control. 1 June 2016. Retrieved 8 June 2016.
- ^ a b "Salt reduction". Fact sheet. World Health Organization. 30 June 2016. Retrieved 10 June 2016.
- ^ a b c "Most Americans Should Consume Less Sodium". Centers for Disease Control and Prevention, U.S. Department of Health & Human Services. 11 July 2019. Retrieved 30 September 2019.
- PMID 23124030.
- ^ "Salt reduction guide for the food industry" (PDF). Foodtech Canada. Archived from the original (PDF) on 17 April 2018. Retrieved 8 June 2016.
- PMID 322597.
- S2CID 9814212.
- ^ PMID 34164803.
- ^ PMID 15478706.
- ^ PMID 11136953.
- ^ a b c "Get the Scoop on Sodium and Salt". American Heart Association. 16 April 2018. Retrieved 30 September 2019.
- ^ PMID 17463420.
- PMID 16434724.
- PMID 23558162.
- PMID 20226955.
- ^ PMID 32626425.
- ^ PMID 26888870.
- ^ Melinda Wenner Moyer (Jul 8, 2011). "It is Time to End the War on Salt: The zealous drive by politicians to limit our salt intake has little basis in science". Scientific American.
- ^ a b "CDC's Sodium Reduction Initiative: Saving Lives and Money" (PDF). US Centers for Disease Control and Prevention. December 2015. Retrieved 9 June 2016.
- ^ "Shaking the Salt Habit". American Heart Association. 2016. Retrieved 9 June 2016.
- ^ "Sodium in Canada". Food and Nutrition. Health Canada. 8 June 2012. Retrieved 10 June 2016.
- ^ "Sodium: The facts" (PDF). US Centers for Disease Control and Prevention. April 2016. Retrieved 10 June 2016.
- PMID 1910064.
- .
- ^ "Survey on Members States' Implementation of the EU Salt Reduction Framework" (PDF). European Commission. 2012. Retrieved 10 June 2016.
- S2CID 25794555.
- PMID 1424217.
- ^ PMID 8613190.
- ^ PMID 9931076.
- PMID 3653973.
- S2CID 2992513.
- S2CID 13888960.
- PMID 10775552.
- ^ PMID 7733391.
- ^ PMID 4036845.
- ^ "Sodium (Survey from 2004 updated to July 2007)". Statistics Canada. 2007.
- ^ PMID 22062728.
- PMID 577961.
- .
- PMID 9022569.